It cannot be used as a regular jacket. You can wear it over a jacket or over a leather one, or dress with different layers. It keeps all the rain on top of it and everything underneath remains dry. It is windproof and has very good waterproofing. It was used on a trip to Amsterdam where it kept me completely dry during bike rides. In terms of sizes, choose the one you generally wear, but its fit is slightly wider. Ideal for having other layers underneath.